Exhaust silencer for internal-combustion engines



Patented Mar. 6, 1923.

UNITED' STATES JOHN REED,OF' CORBRIDGE-PON-TYNE, ENGLAND.

EXHAUSI SILENCER FOR INTERNAL-COMBUSTION ENGINES.

Application filed May 6,

Be it known that I, JOHN REED, a of the King of Great Britain, residing at Corbridge House, (Iorbridge-upon-Tyne, Northumberland, England, have invented certain new and useful Improvements in Exhaust Silencers for Internal-Combustion Engines, of which the following is a specificat1on.

The object of the present invention is to provide an improved silencing device of simple construction, whereby noises caused bygases or air leaving a chamber will be entirely obviated, or so much minimized as to be negligible. The silencer according to this invention and as hereafter described, is particularly applicable for use With internal combustion engines, and may be employed for silencing the exhaust gases thereof, so that the same shall be practically inaudible while producing the least possible back pressure.

According to this invention an elongated outer casing of substantially equal diameter throughout its length is constructed having an open-ended tube ente-ring at-one end and extending to near the opposite closed end of the outer casing, the said open-ended tube having series of holes formed in its wall within the casing, the holes towards the inner end of the tube being larger in area than theholes towards the entering end of the tube; or alternatively the tube within the casing may be formed with a slot or slots which increase in arca as they approach the inner end of the said tube. The outer casing is formed with an opening or provided with a tube communicating with the outer casing adjacent to the entrance end of the aforesaid open-ended tube havingthe slots or holes.

In a specification of a prior United States Patent Application Serial No. 376592 filed 26th April 1920, there has been described a silencer device for the exhaust gasesof insubject terna] combustion engines which consisted of a conical outer casing having .an openended tubeentering'said casing at its larger end and extending axiallytherein and ter minating adjacentto the smaller end of the conical casing, and such a tube Was described as having a series of apertures within the casing increasing in arca as they increased in distance from the larger end of thesaid casing, and a pipe or pipes were to 1921. Serial No. 467,484.

be fitted to conve exhaust gases from the engine to within tfie casing at its larger end and the pipes were to be fitted tangentially to cause the gases to spinaroundthe exterior of the internal tube within the said casing.

. The present invention therefore is primarily differentiated from that described in specification Serial No. 376592 in that in the construction according to the resent invention the case is not conical, t e open-ended tube having the graduated apertures does not necessarily extend coaxially with the outer casing, and furthermore the gases are not conveyed to the outer casing in such manner as to produce a spinning motion.

In the apparatus above generally outlined according to the present invention, when exhaust gases from an engine arebeing dealt with, the same are introduced int,that end of the outer casing distant from the open end of the tube having the graduated holes or tapered apertures in its wall and find their exit by the latter tube.

The ihvention will now be further described with reference.to the example of construction shown on the acompanying drawings. i

F ig. 1 is a longitudinal sectional elevation of a silencing device according to this invention suitable for the passage and silencing of the exhaust gases of an internal combustion engine, and Fig. 2 is a vertical cro'ss section on the line XY of Fig. 1.

The silencer consists A of an elongated closed casing '1, and the two ends 2, 3 in this example will be referred to'respectively as the f0rward'and rearward ends.

Entering the rearward end 3 of the casing by a suitable joint is what will be termed in this example an outlet tube 4 which extends inside the casing 1 to adjacent the forward i end 2 where the end of the outlet tube 4 is open, the said outlet tube being also open at its rearward end externally of the rear end of the casin 1.

The wall of the outlet tube 4Wiifihlfl the casing 1 may be formed with a series of holes graduated or. varying in l diameter, thatis to say the holes towards the rear Ward end 3 of the casing in the wall of the outlet tube being smaller in arca than the holes as they approach the front end of the casing; Alternatively and as shown at Figs. 1 and 2, instead of the holes a slotor slots 5 is or are formed through the wall of the outlet tube 4, the slots increasing in arca as tube.

In the construction shown the inlet tube 6 entere the forward end 2 of the casing 1, and its inner open end terminates adjacent to'the rearward end 3 of the interior of the casing, so that the gases delivered into the casing are so delivered adjacent to the rearward end. Obviously such an inlet tube 6 tor the exhaust gases might enter the casing directly at or near the rearward end 3 when no further tubing would be required in the interior of the casing, or equally obviously the tube 6 might enter the casing at any point and then pass through the interior of the casing, but it is one of the essentials of this invention that the gases should pass to the casing 1 adjacent to the rear end 3 and leave through the graduated slots or open end of the tube 4 at the opposite end of the casing, and in dealing with the exhaust gases from the engine cylinders, the said gases must enter the casing 1 near the end 8 and leave the casing through the graduated apertures or slots 5 of the tube 4 and through the open end thereof near the opposite end of the casing 1.

The forward and rearward ends of the casing may be sloped or curved, and the said ends are preferably of. thicker metal than the remainder of the casing; if made of sheet metal the ends are preferably slightly coned or domed to prevent any possibility of their producing a drumming action or acting as diaphragms, and if so formed they will have the further advantage of deflecting the exhaust gases entering the silencel awa from the inlet tube 6 and thus reducing bae i pres sure, particularly when the inlet tube 6 extends through the length of the interior of the Casing as illustrated in this example.

The action of the silencer is as follows. When an impulse, due to the liberation of the exhaust gas trom the engine enters the silencer, a wave of pressure is set up and travels up the silencer from the rear to the front end. Some ofthis immediately es capes into the outlet tube 4 through the small end of the graduated slot or series of holes 5. The remainder travels up the silencer from the rear to the front being gradually relieved as it travels up the silencer by the graduated slot or series of holes 5, until, when it reaches the front end 2, the whole of the remainder is allowed to escape down the open end of the outlet tube 4.

As part of the impulse escapes immediately through the small end of the slot or series of holes 5 into the outlet tube 4 whilst the remainder has to travel varying distances up to a maximum of twice the length of the slot or series of holes 5, that is once up outside the outlet tube 4 to the open end and back inside it, the effect is to spread out the sound of the impulse over an appreciable period of time and thus reduce its in tensity at any one time. In the case of engines with a large number of cylinders running at a high speed this period of time may actually be greater than the period between the exhausting of one cylinder and the next, and thus almost complete silence may be obtained.

The advantages are that as the silencer does not depend on baflling to obtain silence, the passages may be large and thus reduce back pressure to a minimum. Furtherthe effect of sooting up is. not to cause back pressurebut merely to close up the small end of the slot or series of holes 5,thus in efl'eot shortening it and thus only reducing the degree of silence instead of causing back pressure. Further as the passages can be large they are not as liable to soot up as in the usual construction of silencers. The Outlet tube 4 can be made easily removable for cleaning. The silencer may be sup ported in any convenient manner such as by straps round the barre]. or by brackets.

The tubes 4, 6 may be supported and.hcld in position by any suitable means, such as by brackets 7 8.

What claim as my invention anddesire to secure by Letters Patent is l. n a device for silencing rapidly flowing gases, an elongated outer casing closed at one end and of Substantially uniform diameter throughout its length, in combina tion with a tube open at both ends travers ing nearly the whole length of said casnrg, said tube being provided with communicat means for permitting the passage ofa portion of said gases between its interior space and the surrounding space within the casing, said means bein of maximum area at the open end of said tube adjacent the closed end of said casing, and of gradually diminishing arca towards the other end thereof.

2. In a device for silencing rapidly flowing gases, an elongated outer casing closed at one end and of substantially uniform diameter throughout its length, in combination with a tube open at both ends traversing nearly the whole length of said casing, said tube having a tapering longitudinal slot the maximum width of which is at the open end of said tube adjacent the closed end of said casing.

3. In a device for silencing rapidly flowing gases, an elongated outer casing closed at one end and of substantially uniform diameter throughout its length, in combination with a tube open at both ends traversing nearly the whole length of said ca's1 ng, said tube having a plurality of slots giving communication between its interior space and the surrounding space within the cas ing, the -maximum combined arca of said slots being about the open end of said tube adjacent the closed end of said casing and said combined arca gradually diminishing towards the other end of said tube.

4. In a device for silencing rapidly flowing gases, an elongated outer casing closed at one end and of substantially uniform diameter throughout its length, in combination with a tube open at both ends traversing nearly the whole length of said casing, said tube having a trumpet-mouthed longitudinal slot, the flared end of which is at the open end of said tube adjacent the closed end of said casing.

In a device for silencing rapidly flowing gases escaping from an internal combustion engine, an elongated outer casing closed at one end and of substantially uniform diameter throughout its length, an open ended tube entering at one end and extending to near the opposite closed end of said casing, said tube being formed with a slot which increases in diameter as it approaches the inner end of said tube, and means for admitting said escaping gases to the interior of said casing adjacent that end of said casing at which said tube enters.

6. In a device for silencing rapidly flowing gases escaping from an internal combustion engine, an elongated outer casing closed at one end and of substantially unifornt diameter throughout its length, an open-ended tube entering at one end and ex tending to near the opposite closed end of said casing at one side of the major axis of said casing, said tube being formed with a slot which increases in dameter as it approaches the inner end of said tube, in combination with a second tube entering said casing through said closed end and extending parallel with the said first named tube to deliver said escaping gases to the interior of said casing adjacent that end of said casing at which said first named tube enters.

7. In a device for silencing rapidlv flowing gases escaping from an internal com hustion engine, an elongated outer casing of substantially uniform diameter throughout its length and. having an inclined closed end, an open-ended tube entering said casing at the end opposite said inclined closed end and extending nearly to said inclined closed end, said tube being formed with a slot which increases in diameter as it approaches the inner end of said tube, and means for admitting said escaping gases to the interior of said casing adjacent that end of said casing at which said tube enters.

8. In a device for silencing rapidly flowing gases escaping from an internal combustion engine, an elongated outer casing of sub-stantially uniform diameter throughout its length and having two inclined closed ends, two open-ended. tubes entering said casing adjacent said closed ends and each of said tubes extending in parallel relation to the other tube nearly to the opposite inclined end of said casing, one of said tubes being formed with a slot which slot increases in diameter as it approaches the inner end of said tube.

9. In a device for silencing rapidly flowing gases escaping from an internal combustion engine, an elongated outer casing of substantially uniform diameter throughout its length and having a domed closed end, an opencnded tube entering said casing at the end opposite said domed closed end and extending nearly to said domed closed end, said tube being formed with a slot which increases in diameter as it approaches the inner end of said tube, and means for admitting said escaping gases to the interior of said casing adjacent that end of said casing at which said tube enters.

10. In a device for silencing rapidly flowing gases escaping from an internal combustion engine, an elongated outer casing of substantially uniform d1ameter throughout its length and having two domed closed ends, two open-ended tubes entering said casing adjacent said closed ends and each of said tubes extending in parallel relation to the other tube nearly to the opposite domed end of said casing, one of said tubes being formed with a slot Which slot increases in diameter as it approaches the innerend of said tube.

In witness whereof I have hereunto set my hand in the presence of two witnesses.

JOHN REED.

W itnesses HILDA MACLE0D, FLORENCE DAVEY. 

